datatypes example

(define-datatype arbol arbol?
  (arbol-empty)
  (arbol-leaf (num number?))
  (arbol-int (key number?)
             (left arbol?)
             (right arbol?))
  (arbol-symbol (key symbol?)
                (left arbol?)
                (right arbol?)))



;;sintaxis abstracta
(define arbol1 (arbol-empty)) ;;debe de dar 0
(define arbol2 (arbol-int 5
                          (arbol-empty)
                          (arbol-symbol 'g
                                        (arbol-symbol 'p
                                                      (arbol-empty)
                                                      (arbol-int 4
                                                                 (arbol-leaf 3)
                                                                 (arbol-leaf 9)))
                                        (arbol-leaf 2)))) ;; debe de dar 23

(define arbol3 (arbol-leaf 7)) ;; debe de dar 7


;;suma de numeros
(define suma-numeros
  (lambda (arb)
    (cases arbol arb
      (arbol-empty ()0)
      (arbol-leaf (num) num)
      (arbol-int (k l r)
                 (+ k
                    (suma-numeros l)
                    (suma-numeros r)))
      (arbol-symbol (k l r)
                    (+ (suma-numeros l)
                       (suma-numeros r))))))